<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <style>
        .INPUT{
            width: 130px;
            height: 30px;
        }
        .INPUT:focus{
            width: 100%;
            transform: all 0.5s ease-in;
        }
        ul{
            display: flex;
        }
        ul li{
            list-style: none;
            width: 50px;
            height: 50px;
            border: 1px solid #ddd;
            text-align: center;
            line-height: 50px;
        }
        li:hover{
            background-color: #4caf50;
            /* margin: 10px;  */
            color: white;
        }
    </style>
    <ul>
        <li><<</li>
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li>5</li>
        <li>>></li>
    </ul>
    <input type="text" placeholder="请输入内容..." class="INPUT">
</body>
</html>